Develop Reference

OData Bad Request 400 with Java Client

I have an issue regarding OData querying with an Java Client.
If I use Postman, everything works as expected and I'm receiving a response from the web service with the metadata. But in my Java Client, which runs not on the SCP / HCP I'm receiving "400-Bad Request". I used the original Olingo libary.
I only used the $metadata Parameter, so there is no filter value or something else.
public void sendGet(String user, String password, String url) throws IOException, URISyntaxException {
// String userPassword = user + ":" + password;
// String encoding = Base64.encodeBase64String(userPassword.getBytes("UTF-8"));
URL obj = new URL(url);
URL urlToEncode = new URL(url);
URI uri = new URI(urlToEncode.getProtocol(), urlToEncode.getUserInfo(), urlToEncode.getHost(), urlToEncode.getPort(), urlToEncode.getPath(), urlToEncode.getQuery(), urlToEncode.getRef());
// open Connection
HttpURLConnection con = (HttpURLConnection) uri.toURL().openConnection();
// Basis Authentifizierung
con.setRequestProperty("Authorization", "Basic " + user);
// optional default is GET
con.setRequestMethod("GET");
// add request header
con.setRequestProperty("Content-Type", "application/xml");
int responseCode = con.getResponseCode();
System.out.println("\nSending 'GET' request to URL : " + url);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
response.append("\n");
}
in.close();
// print result
System.out.println(response.toString());
// Schließt eine Vorhandene Verbindung
con.disconnect();
in User is already the encoded value. by manipulating this one, i'm receiving an authorization error, so already tested.
May somebody can help me in that case :)
Thanks in advance.
Tim

So I solved it by myself.
i added the statement con.setRequestProperty("Accept", "application/xml"); and it works fo me.
Maybe it could help somebody else.

Java Post Connection Using Try with Resources

I want to implement the code for handling POST requests using try with resources.
Following is my code:
public static String sendPostRequestDummy(String url, String queryString) {
log.info("Sending 'POST' request to URL : " + url);
log.info("Data : " + queryString);
BufferedReader in = null;
HttpURLConnection con = null;
StringBuilder response = new StringBuilder();
try{
URL obj = new URL(url);
con = (HttpURLConnection) obj.openConnection();
// add request header
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", "Mozilla/5.0");
con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
con.setRequestProperty("Content-Type", "application/json");
// Send post request
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(queryString);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
log.info("Response Code : " + responseCode);
if (responseCode >= 400)
in = new BufferedReader(new InputStreamReader(con.getErrorStream()));
else
in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
}catch(Exception e){
log.error(e.getMessage(), e);
log.error("Error during posting request");
}
finally{
closeConnectionNoException(in,con);
}
return response.toString();
}
I have the following concerns for the code:
How to introduce conditional statements in try with resources for the above scenario?
Is there a way to pass on the connection in try with resources? (It can be done using nested try-catch blocks since URL and HTTPConnection is not AutoCloseable, which itself is not a compliant solution)
Is using try with resources for the above problem is a better approach?

Try this.
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
try (AutoCloseable conc = () -> con.disconnect()) {
// add request headers
try (DataOutputStream wr = new DataOutputStream(con.getOutputStream())) {
wr.writeBytes(queryString);
}
int responseCode = con.getResponseCode();
try (InputStream ins = responseCode >= 400 ? con.getErrorStream() : con.getInputStream();
BufferedReader in = new BufferedReader(new InputStreamReader(ins))) {
// receive response
}
}
() -> con.disconnect() is a lambda expression which execute con.disconnect() at finally stage of the try statement.

1: You can use conditional statements inside try with resources statement also. Unfortunately you have to define new variable for this block and cannot use a predefined variable. ( variable in in your code)
try (BufferedReader in = (responseCode >= 400 ? new BufferedReader(new InputStreamReader(con.getErrorStream())) : new BufferedReader(new InputStreamReader(con.getInputStream())))) {
// your code for getting string data
}
2: I'm not sure HttpUrlConnection is AutoCloseable, So it might be a good idea to call the disconnect() yourself. I'm open to any suggestion on this one.
3: try with resources will definitely help you in managing the resources. But if you're confident that you're releasing the resources properly after use, then your code is fine.

POST params empty, what am I doing wrong? HttpURLConnection / Android / Java

The code below shows a method, downloadUrl(), that takes a String, "myurl," its parameter. There are only two possible urls that I ever send to it, and the behavior of the method is different for each.
when myurl = URL1, it uses a GET request and everything works fine.
when myurl = URL2, however, it uses a POST request, and the response from the php page indicates that the post parameters sent with the request were empty. You can see the line where I set the POST params, so I don't understand why it's sending no params?!
Thanks for any help!
-Adam.
private String downloadUrl(String myurl) throws IOException {
InputStream is = null;
String response = "";
try {
URL urlObject = new URL(myurl);
HttpURLConnection conn = (HttpURLConnection) urlObject.openConnection();
// find out if there's a way to incorporate these timeouts into the progress bar
// and what they mean for shitty network situations
conn.setReadTimeout(10000 /* milliseconds */);
conn.setConnectTimeout(15000 /* milliseconds */);
conn.setDoInput(true);
// INSERTED QUICK CHECK TO SEE WHICH URL WE ARE LOADING FROM
// it's important because one is GET, and one is POST
if (myurl.equals(url2)){
Log.i(TAG, "dlurl() in async recognizes we are doing pre-call");
conn.setRequestMethod("POST");
conn.setDoOutput(true);
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
String postParams = "?phone=" + phone;
writer.write(postParams);
Log.i(TAG, "we're adding " + postParams + "to " + urlObject);
writer.flush();
writer.close();
os.close();
}
else {
conn.setRequestMethod("GET");
conn.connect();
}
// Starts the query
int responseCode = conn.getResponseCode();
Log.i(TAG, "from " + myurl + ", The response code from SERVER is: " + responseCode);
is = conn.getInputStream();
// Convert the InputStream into a string
// i guess we look up how to do this
if (responseCode == HttpsURLConnection.HTTP_OK) {
String line;
BufferedReader br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
response += line;
}
} else {
response = "from downloadUrl, php page response was not OK: " + responseCode;
}
// it's good to close these things?
is.close();
conn.disconnect();
Log.i(TAG, "response is " + response);
return response;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} finally {
if (is != null) {
is.close();
}
}
}

try with following code block to send parameters of the POST request.
Map<String,String> params = new LinkedHashMap<>();
params.put("phone", "phone");
StringBuilder postPraamString = new StringBuilder();
for (Map.Entry<String,Object> param : params.entrySet()) {
if (postPraamString.length() != 0) postPraamString.append('&');
postPraamString.append(URLEncoder.encode(param.getKey(), "UTF-8"));
postPraamString.append('=');
postPraamString.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8"));
}
byte[] postDataBytes = postData.toString().getBytes("UTF-8");
writer.write(postDataBytes);

So I figured out the root of the problem...
In the line:
String postParams = "?phone=" + phone;
The problem was that leading question mark. The question mark should only be used in GET requests.

Why Google Recaptcha returns false after a specific time in java?

I am using Google reCAPTCHA in my project. It works fine. But after a specific time, my code is returning the response value is false. It should be true.
Not always like this, but after 10 days(for example) returning false.I am not hitting any daily usage limit.
The problem is solving when I restart the server (apache tomcat).
My code is:
public static boolean verify(String gRecaptchaResponse) throws IOException {
if (gRecaptchaResponse == null || "".equals(gRecaptchaResponse)) {
return false;
}
try {
URL obj = new URL(url);
HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
// add reuqest header
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", USER_AGENT);
con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
String postParams = "secret=" + secret + "&response="
+ gRecaptchaResponse;
// Send post request
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(postParams);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + postParams);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(new InputStreamReader(
con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
// print result
System.out.println(response.toString());
//parse JSON response and return 'success' value
JsonReader jsonReader = Json.createReader(new StringReader(response.toString()));
JsonObject jsonObject = jsonReader.readObject();
jsonReader.close();
return **jsonObject.getBoolean("success");**
} catch(Exception e){
e.printStackTrace();
return false;
}
}

cURL command to Java

I have a cURL command I want to translate in Java
curl -H "Key: XXX" -d url=http://www.google.com http://myapi.com/v2/extraction?format=json
It works fine.
I started to do in Java: (CODE EDITED, it works)
try {
// POST
System.out.println("POSTING");
URL url = new URL("http://myapi.com/v2/extraction?format=json");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
connection.setRequestProperty("Key", "XXX");
String data = "http://www.google.com";
OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
writer.write("url=" +data);
writer.close();
int responseCode = connection.getResponseCode();
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + data);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
System.out.println("REPOSNE" +response.toString());
if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
// OK
} else {
// Server returned HTTP error code.
}
} catch (MalformedURLException e) {
// ...
} catch (IOException e) {
// ...
}
But I don't know how to set my arguments.
Thanks for your help.
Jean

If you mean to set a header field Key with value XXX you can use the setRequestProperty
ie
conn.setRequestProperty("Key", "XXX");
If you want to send data, use
String data = "url=http://www.google.com";
conn.setRequestProperty("Content-Length", "" + Integer.toString(data.getBytes().length));
EDIT:-
For posting data as form url encoded, try the following code
String data = "url=" + URLEncoder.encode("http://www.google.com", "UTF-8");
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
wr.write(data.getBytes());